There also has been an increase in car models with photovoltaic solar panels in the roof. “The military has been developing battery panels and embedded solar panels for years,” says Gary Lownsdale, president of Trans Tech International (Loudon, TN, US). “Again, hybrid composite materials offer a lot of opportunity, for example adding carbon nanotubes and other nanomaterials. Embedding flexible electrical circuits in body panels is also an attractive development because you can get rid of the wiring harnesses and simplify the supply chain and assembly.”